Strain Wave Gear Tooth Geometry for Compact High-Torque Drives
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Solution Overview
Problem
Conventional strain wave gears face issues with a large radial design size and torque transmission ratio, leading to problems like ratcheting, jamming, increased wear, and tooth tip collisions, especially when transmitting larger torques.
Innovation Solution
A strain wave gear design with a reduced rim thickness and specific tooth configuration, including a profile angle of 8 to 14 degrees, allows for a larger torque transmission ratio without additional radial stabilization, using materials like iron, steel, or titanium, and optimizing the number of teeth and modulus to achieve a compact and robust construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the rim thickness of the outer ring is reduced to achieve a compact radial design size, then the radial design size is improved, but the structural strength and stability deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the ratio of pitch diameter to rim thickness to fall within 13 to 21 (preferably 17 to 19), and by setting specific profile angles for the teeth (8 to 12 degrees for inner ring, 8 to 14 degrees for outer ring). These parameter optimizations allow the outer ring to maintain sufficient structural strength while achieving a compact radial design size, resolving the contradiction between compactness and strength.
2Power
If the torque transmission ratio is increased to improve power capacity, then the power transmission capability is improved, but harmful effects such as ratcheting, jamming, and tooth tip collisions increase
Solution Approach 1:
The patent resolves this contradiction by optimizing key parameters: the pitch diameter to rim thickness ratio (13 to 21) ensures adequate load distribution, while the specific profile angles (8 to 12 degrees for inner ring teeth, 8 to 14 degrees for outer ring teeth) prevent tooth tip collisions and reduce ratcheting. These parameter changes enable high torque transmission capability while minimizing harmful effects.
Solution Approach 2:
The patent applies local quality by designing different profile angles for the inner and outer ring teeth according to their specific functional requirements. The inner ring teeth have a profile angle of 8 to 12 degrees while the outer ring teeth have 8 to 14 degrees, optimizing the local contact characteristics at each engagement point to reduce harmful effects while maintaining high torque capacity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables a compact strain wave gear that transmits larger torques with reduced radial size, minimizing wear and noise while maintaining high torque capacity and operational reliability.
Implementation Method 1
a flexible inner ring with an outer toothing engages at two opposing points
Data Source
AI summary
The invention relates to a strain wave gear, having an outer ring with an inner toothing, with which a flexible inner ring with an outer toothing engages at two opposing points. The strain wave gear is characterized in that the ratio of the pitch diameter of the outer ring to the rim thickness of the outer ring lies in the region of 13 to 21, especially in the region of 17 to 19, especially at 17.587, wherein the teeth of the toothing of the inner ring have a profile angle in the region of 8 degrees to 15 degrees or in the region of 11 degrees to 12 degrees or one of 11.615 degrees, and/or wherein the teeth of the toothing of the outer ring have a profile angle in the region of 8 degrees to 15 degrees or in the region of 11 degrees to 13 degrees or one of 12.474 degrees.